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| United States Patent |
5,122,420
|
|
Baron
, et al.
|
June 16, 1992
|
Components made from continuous fiber reinforced polyamide molding
compositions and rubber, and a process for their preparation
Abstract
Components made from at least two molded materials A and B which are firmly
bonded together, and in which
a) the molded material A is composed of a matrix of polyamide or of a
polyamide-containing molding composition and of a continuous, fibrous
reinforcement embedded therein, and
b) the molded material B is the rubber obtained after peroxidic
vulcanization of a rubber composition which is applied to A, the rubber
composition containing the following components:
i) about 100 parts by weight of a rubber having carboxyl or anhydride
functional groups;
ii) about 10 to 300 parts by weight of fillers; and
iii) about 1 to 10 parts by weight of peroxidic vulcanizing agents.
| Inventors:
|
Baron; Christian (Haltern, DE);
Grosse-Puppendahl; Thomas (Haltern, DE);
Jadamus; Hans (Marl, DE);
Richter; Klaus-Peter (Marl, DE)
|
| Assignee:
|
Huls Aktiengesellschaft (Marl, DE)
|
| Appl. No.:
|
573827 |
| Filed:
|
August 28, 1990 |
Foreign Application Priority Data
| Current U.S. Class: |
428/474.4; 427/385.5; 427/393.5; 428/492; 428/521; 428/522 |
| Intern'l Class: |
B32B 027/08; B32B 025/08; B05D 003/02 |
| Field of Search: |
428/357,474.4,492,521,522
525/105,285,133
427/385.5,393.5
|
References Cited
U.S. Patent Documents
| 3518278 | Jun., 1970 | Suh | 546/80.
|
| 4010223 | Mar., 1977 | Caywood, Jr. | 525/285.
|
| 4339376 | Jul., 1982 | Kasahara et al. | 525/133.
|
| 4844944 | Feb., 1989 | Graefe et al. | 428/357.
|
| 5006603 | Apr., 1991 | Takaki et al. | 525/105.
|
Primary Examiner: Herbert, Jr.; Thomas J.
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier & Neustadt
Claims
WHAT IS CLAIMED AS NEW AND DESIRED TO BE SECURED BY LETTERS PATENT OF THE
UNITED STATES IS:
1. Components made from at least two molded materials A and B which are
firmly bonded together, and in which
a) the molded material A is composed of a matrix of polyamide or of a
polyamide-containing molding composition and of a continuous, non-metallic
fibrous reinforcement embedded therein, and
b) the molded material B is the rubber obtained after peroxidic
vulcanization of a rubber composition which is applied to A, the rubber
composition containing the following components:
i) about 100 parts by weight of a rubber having carboxyl or anhydride
functional groups;
ii) about 10 to 300 parts by weight of fillers; and
iii) about 1 to 10 parts by weight of peroxidic vulcanizing agents.
2. The components according to claim 1, wherein the polyamide used is PA
46, PA 6, PA 66, PA 610, PA 612, PA 1010, PA 1012, PA 11, PA 12 or PA 1212
or a mixture thereof.
3. The components according to claim 1, wherein the polyamides contain COOH
and NH.sub.2 terminal groups in a ratio of 1:x where 100>x>1.
4. The components according to claim 1, wherein the polyamide-containing
molding composition contains up to 70% by weight of a polyphenylene ether,
relative to the total amount of polyphenylene ether and polyamide.
5. The components according to claim 1, wherein the reinforcements are
composed of glass fibers, aramid fibers or carbon fibers or a mixture
thereof which are present in the form of yarns, fabrics, mats, webs, UD
tapes, laid fabrics, rovings or as individual fibers.
6. The components according to claim 1, wherein the rubber composition
contains a carboxyl- or anhydride-containing EP(D)M or NBR rubber.
7. The components according to claim 1, wherein the fillers used int he
rubber composition are carbon black, silica, silicates, calcium carbonate,
zinc oxide or stearic acid or a mixture thereof.
8. The components according to claim 1, wherein said rubber composition of
molded material B further contains from 0 to 4 parts by weight of
vulcanization activators.
9. The components according to claim 1, wherein said rubber composition of
molded material B further contains from 0 to 150 parts by weight of
plasticizer.
10. The components according to claim 9, wherein the plasticizer used is up
to 50 parts by weight of naphthenic oils, relative to 100 parts by weight
of rubber.
11. A process for the preparation of the components according to claim 1,
which comprises completely enclosing said fibrous reinforcements with
polyamide or with a polyamide-containing molding composition, applying the
rubber composition to the molded material A which has been prepared in
this manner and vulcanizing the rubber composition.
12. The process according to claim 11, wherein the vulcanization is carried
out at temperatures of between 140.degree. and 200.degree. C. for 3 to 30
minutes.
13. The process according to claim 12 wherein the vulcanization is carried
out at temperatures of between 150.degree. and 180.degree. C. for 5 to 15
minutes.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to components which are composed of at least
one continuous fiber reinforced thermoplastic polyamide component and one
rubber component, which are bonded together without the use of coupling
agents or adhesives.
2. Description of the Background
A single material cannot always provide all of the properties which are
required of an object. Some property combinations are irreconcilable, such
as for example, high strength, rigidity or hardness on the one hand and
good vibration-damping, high elasticity and non-skid properties on the
other hand. If a component is to combine these properties, composites of a
plurality of materials are used.
In principle, it might be thought that composites having the above combined
properties could be prepared from metal and rubber. However, this
combination of materials has significant disadvantages:
1. Metals have a high density, i.e., the components produced from them are
heavy.
2. Without a coupling agent, a primer or an adhesive it is not possible to
bond metal and rubber.
3. It is very costly to prepare complex components such as, for example,
three-dimensional structures from metal.
Continuous-fiber-reinforced thermoplastics are, for example, described in
R. F. McMahon "Developments in Reinforced Plastics-4", Elsevier Applied
Science Publishers, 1984, and also in G. Brandt and H. Richter,
Kunststoffe 77 (1987), P. 40. The systems described in these articles
would satisfy the above-mentioned strength, rigidity and hardness
requirements; however, examination shows that the reinforced plastics
which have been described do not form a firm bond with rubber. The
vulcanized rubber can be peeled from the interface with the thermoplastic
by a small force, i.e., of less than 0.7 N/mm, in the case of a carbon
fiber/polyether ether ketone/E-SBR rubber composite. Such a low level of
adhesion is quite unsatisfactory for industrial purposes.
DE-A-3,615,965 discloses the preparation of a firm bond between
continuous-fiber-reinforced polyphenylene ether molding compositions and
certain rubbers containing double bonds, such as, for example,
styrene-butadiene rubber. The adhesions achieved by this method are
considerable, but the solvent resistance and also the weathering
resistance of the polyphenylene ether molding compositions which are used
are unsatisfactory. Hence, the conventional methods cannot therefore
provide a simple preparation of components which is composed on the one
hand of continuous-fiber-reinforced thermoplastics and on the other hand
of rubber, and which additionally has good solvent and weathering
resistance.
Further, EP-A-0,344,427 discloses a process for the preparation of a
chemical bond between molding compositions based on aliphatic polyamides
on the one hand and carboxyl-containing rubbers on the other hand, as well
as materials prepared by the process. However, there is no indication
therein that non-metallic fibers can be used.
Thus, a need clearly continues to exist for a simple preparation of
components which are composed of at least one continuous fiber reinforced
thermoplastic and a rubber component, and which has, at once, excellent
solvent and weathering resistance.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a simple
preparation of components which are composed of at least one continuous
fiber reinforced thermoplastic and a rubber component which has, at once,
excellent solvent and weathering resistance.
It is also an object of this invention to provide a process for preparing
the components described above.
The above objects and others which will be described hereinbelow are
provided by components made from at least two molded materials A and B
which are firmly bonded together, wherein:
a) the molded material A is composed of a matrix of polyamide (PA) or of a
polyamide-containing (PA-containing) molding composition and of a
continuous, fibrous reinforcement embedded therein, and
b) the molded material B is the rubber obtained after peroxidic
vulcanization of a rubber composition which has been applied to A, the
rubber composition containing the following components:
i) about 100 parts by weight of a rubber having carboxyl or anhydride
functional groups;
ii) about 10 to 300 parts by weight of fillers; and
iii) about 1 to 10 parts by weight of peroxidic vulcanizing agents.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The fibrous reinforcement of the molding compositions based on PA are
composed of continuous non-metallic fibers such as, for example, carbon
fibers, aramid fibers and/or glass fibers. The fibers may, for example, be
present in the form of yarns, fabrics, mats, webs, UD tapes, laid fabrics,
rovings or as individual fibers. Normally, the fibers are treated with a
size by the producer. The rigidity and strength of the
continuous-fiber-reinforced PA molding compositions are accordingly
determined by the type, alignment and proportion of the fibrous
reinforcements and by the composition of the matrix.
The polyamides used according to the invention have --CO--NH-- bonds in
their main chain. Any polyamides which can be melted by heating are
suitable. Particular examples of suitable polyamides are PA 46, PA 6, PA
66, PA 610, PA 612, PA 1010, PA 1012, PA 11, PA 12 and/or PA 1212. The
polyamides are prepared by polycondensation in a known manner. The ratio
of COOH groups to NH.sub.2 groups in the polyamide is preferably 1: x
where 100 >x>1.
The molding compositions based on PA may, for example, contain
polyphenylene ethers. Suitable polyamide/polyphenylene ether molding
compositions are prepared by melting and mixing at least 30 percent by
weight of a polyamide with up to 70 percent by weight of a polyphenylene
ether. Molding compositions based on polyamides and polyphenylene ethers
are described, for example, in DE-A-3,027,104 and 3,518,278 and also in
EP-A-0,147,874 and EP-B-0,024,120. It is known to those skilled in the art
that these molding compositions normally contain a compatibilizer.
Furthermore, the molding compositions optionally contain further additives
such as, for example, stabilizers, processing auxiliaries, carbon black,
graphite, titanium dioxide, zinc sulphide, pigments, impact modifiers and
flame retardants. The proportion of these additives is preferably below
30%, relative to the total molding composition.
The rubber composition used to prepare the rubber component B contains an
unvulcanized rubber having carboxyl or anhydride groups which is prepared,
for example, in a known manner by carboxylation using unsaturated acids or
acid derivatives such as, for example, maleic acid or maleic anhydride
(cf., for example, U.S. Pat. No. 4,010,223). It is also possible to
prepare these unvulcanized rubbers by copolymerization with unsaturated
acids, such as, for example, acrylic acid. In principle, any unvulcanized
rubbers containing carboxyl or anhydride groups, which can be prepared in
a known manner are suitable. However, preference is given to carboxyl- or
anhydride-containing EP(D)M rubbers and NBR rubbers.
EP(D)M rubbers are rubbers which are prepared in a known manner by
polymerization of a mixture of ethylene and propylene and optionally a
diene in the presence of a Ziegler-Natta catalyst.
The EPDM rubber is prepared, for example, by polymerizing a mixture of more
than 25% of ethylene, more than 25% of propylene and 1 to 10%, in
particular 1 to 3%, of a non-conjugated diene such as
(2.2.1)-bicycloheptadiene, 1,4-hexadiene, dicyclopentadiene and, in
particular, 5-ethylidenenorbornene.
Suitable EPM rubbers are produced, for example, by the EXXON company under
the trade name EXXELOR VA 1803 (trade mark applied for). An example of a
suitable EPDM rubber is maleic anhydride-modified BUNA.RTM. AP (product
designation: experimental product X 4496) from Bunawerke Huls GmbH, D-4370
Marl.
Nitrile rubbers (NBR) are prepared by copolymerizing 50 to 80% by weight of
butadiene and correspondingly 50 to 20% by weight of acrylonitrile.
Carboxyl-containing nitrile rubbers are an example of particular
modifications which may be used. In particular, they are copolymers of
butadiene, acrylonitrile and acrylic acid, methacrylic acid or sorbic
acid.
Suitable NBR rubbers are produced, for example, by Goodyear Tire & Rubber
Company, Akron, Oh., USA, under the trade name CHEMIGUM.RTM. NX 775 and by
BF Goodrich, NV, Arnhem, Netherlands, under the trade name HYCAR.RTM.
1472.
Suitable fillers are any such materials which are normally added to EP(D)M
and NBR rubbers, such as, for example, carbon black, silica, silicates,
calcium carbonate, zinc oxide and/or stearic acid.
The rubber composition can contain up to 150 parts by weight of plasticizer
per 100 parts by weight of rubber. Examples of suitable plasticizers are
naphthenic oils or synthetic plasticizers such as esters or ethers,
preferably in an amount of up to 50 parts by weight, relative to 100 parts
by weight of rubber.
Suitable peroxidic vulcanizing agents are the peroxides which are known to
those skilled in the art, such as, for example,
2,5-dimethyl-2,5-bis(tert-butyl-peroxy)hexane, dicumyl peroxide,
4,4-di-tert-butylperoxy-n-butyl valerate,
1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane and bis
(tert-butylperoxyisopropyl) benzene. Details of the use of peroxidic
vulcanizing agents are given in the commercial literature "Rubbery
Chemical-Crosslinking Peroxides" from Akzo-Chemie (publication date: April
1985).
Examples of suitable vulcanization activators are triallyl cyanurate (TAC)
and acrylates such as ethylene glycol dimethacrylate (EDMA) and
trimethylolpropane trimethacrylate (TRIM). Preference is given to the use
of TAC and/or EDMA.
The vulcanizates have high tensile strength, good elasticity and very good
abrasion resistance. The oil and solvent resistance typical of nitrile
rubbers is unimpaired by the addition of unsaturated acid derivatives
during polymerization.
The shape and dimensions of the molded materials which have been bonded in
the component may differ greatly. They may, for example, be virtually
identical as, for example, in sandwich structures, or different, as for
example in large-area rubber mats having reinforced edges or in large-area
rigid articles having vulcanized rubber feet.
The components according to the invention are essentially prepared in two
steps. First, the continuous-fiber-reinforced polyamide molded material A
is prepared and then the component B is prepared by vulcanizing the rubber
composition which has been applied to A.
The thermoplastic molding composition can be applied to the reinforcement
by various methods. A number of appropriate industrial processes are given
below:
I. In a first step, the fibrous reinforcements are impregnated with a
solution of the thermoplastic. Suitable solvents are any which can
dissolve polyamides, an example being m-cresol. Then the solvent is
removed. Simultaneously or subsequently, the molded material A is given
its shape. This is advantageously carried out at elevated temperature and
optionally with the application of a vacuum or an excess pressure. This
method can be used to impregnate not only rovings but also fabrics and UD
tapes, for example.
II. The fibrous reinforcements such as, for example, fabrics and UD tapes,
are stacked alternately with thin PA sheets and then formed into the
molded material A by the action of pressure and temperature in a press or
an autoclave.
III. The fibrous reinforcement is coated directly with a PA powder by
sprinkling it on. Then the fabric, with the powder loosely adhering to it,
is passed through a heating zone, preferably on infrared oven, where the
polymer melts and "sticks" to the fibers. The finished prepreg is cooled
by passing it through a calender and can then be shaped as desired, for
example, in a press by the action of pressure and temperature.
IV. If the reinforcement is rovings, the molded material A may also be
prepared by a process which includes the following steps:
1. First, the fiber roving is spread out and wetted with the polymer powder
in a fluidized bed.
2. Then the wetted fiber roving is coated with an extruded film of the same
material.
3. These rovings can then be further processed to form fabrics or UD
prepregs which give the molded material A, for example, in a press under
the action of pressure and temperature.
It is important in every case that in these processes the fibrous
reinforcement is completely enclosed with polyamide or with the
polyamide-containing molding composition.
The components consisting of rigid and rubber-elastic molded materials can
be produced by various methods:
1. By applying the rubber composition to the molded material A and pressing
under vulcanizing conditions.
2. By extrusion coating of pretreated rovings or of previously prepared
rigid moldings with rubber followed by vulcanization.
3. By injection molding rubber around previously prepared rigid components
followed by vulcanization in the same tool.
The optimal vulcanizing conditions are dependent on the rubber mixture
which has been selected, particularly on its vulcanizing system, and also
on the shape of the molding. Suitable vulcanizing temperatures are between
140.degree. C. and 200.degree. C., preferably between 150.degree. C. and
180.degree. C. When using PA materials having low dimensional stabilities
at elevated temperature, vulcanizing temperatures at the lower end of the
given ranges are selected.
The vulcanizing times are normally between 3 and 30 minutes, preferably
between 5 and 15 minutes.
The components according to the invention can be used in many different
ways. If the alignment of the reinforcements is unidirectional, the
components are particularly suitable for peripheral protective elements
for vehicles, such as rubbing strips, door trims or door sill liners.
Another field of application is, for example, conveyor belts, in which the
surfaces may be reinforced in the normal manner using carcasses.
Fields of application in which reinforcements are aligned orthotropically
or quasi-isotropically, include non-skid panels and also doors and flaps
with sealing lips.
Multiple sandwich structures made from thin layers of PA-coated
reinforcements and optionally from reinforced rubber, the reinforcements
preferably having a quasi-isotropic alignment, are used for ballistic
applications (armor-plating).
Having described the present invention, the same will now be further
illustrated by reference to certain examples which are offered solely for
purposes of illustration and are not intended to be limitative.
EXAMPLE 1
Preparation and properties of a composite panel made from a glass fabric/PA
composite and an EPM rubber having functional groups
Starting materials and preparation
1.1 Glass fabric
Commercially available textile fabric W 2415 having a basis weight of 170
g/m.sup.2 from Verseidag Industrietextilien GmbH, D-4150 Krefeld.
1.2 Polyamide
Commercially available PA 12 powder from Huls AG, D-4370 Marl, with the
trade name VESTOSINT.RTM. X7004, having a particle size <45 .mu.m. The
properties of the VESTOSINT.RTM. grades are summarized in the product data
sheet "VESTOSINT BESCHICHTUNGSPULVER" 4151/4, published July 1988.
1.3 Pretreatment of the glass fabric
The polyamide 12 powder is sprinkled uniformly over the glass textile
fabric. The fabric which has been coated in this manner is then passed
into an infrared oven heated to 220.degree. C. where the powder melts,
penetrates the fabric, and sticks to the fibers. The finished prepreg is
cooled by being passed through a calender and wound up. The ration of
glass fiber to polyamide is determined by reweighing.
1.4 Panels made from a glass fabric/PA composite
The previously prepared PA prepregs are stacked in accordance with the
desired panel thickness and pressed at 220.degree. C. and 25 bar, using a
spacer frame, to form panels.
__________________________________________________________________________
Properties of panels (2 mm in thickness)
Ratio by volume of glass
Modulus of elasticity in
Tensile strength in MPa
Elongation at break
fabric to polyamide matrix
tension in MPa (DIN 53 457)
(DIN 53 455)
in % (DIN 53 455)
__________________________________________________________________________
27:73 6,800 240 4.4
__________________________________________________________________________
1.5 Rubber: EXXELOR VA 1803
This is a maleic anhydride-modified EPM rubber from Exxon Chemicals,
Wilmington, Del., USA. The properties of the product can be obtained from
the technical data sheet "EXXELOR VA" published Mar. 1, 1988.
A carbon-black-filled EPM rubber containing plasticizer is prepared on a
mill at 60.degree. C. by mixing the following ingredients:
______________________________________
Parts by weight
Material
______________________________________
100 EXXELOR VA 1803
5 Zinc oxide
60 Paraffin oil "SUNPAR 150"
(Producer: Sunoil, Belgium LV,
Antwerp)
100 DUREX O, a semi-reinforcing gas
black from Degussa, D-6450
Hanau.
1.5 VULKANOX .sup..RTM. HS, an antioxidant from
Bayer AG, D-5090 Leverkusen
(2,2,4-Trimethyl-1,2-
dihydroquinoline)
1.0 Triallyl cyanurate (TAC) from
Degussa, D-6450 Hanau
7.5 PERKADOX .sup..RTM. 14/40 from Akzo-
Chemie, Netherlands (peroxide)
______________________________________
Composite panels with rubber
To demonstrate the bonding action, composite panels are prepared by
covering the panels produced in 1.4 to the extent of one-third with a
Teflon film, placing a rubber hide of suitable dimensions on the panel,
preparing the composite by pressing and finally sawing off test pieces
having a width of 25 mm. These test pieces are subjected to a peel test in
accordance with DIN 53 539.
Result
The following properties are determined from Example 1:
__________________________________________________________________________
Unvulcanized
Vulcanizing temperature
Vulcanizing time
Bond strength in N/mm
Type of separation
rubber in .degree.C.
in min DIN 53 539 c = cohesive a = adhesive
__________________________________________________________________________
1.5 170 15 8.8 c
__________________________________________________________________________
The separation in the peel test (DIN 53 539) occurs cohesively, i.e. the
composite separates within the rubber component and not at the
plastic/rubber interface.
EXAMPLE 2
The selection of starting materials and the preparation of the PA/glass
fabric composite panels are as described under 1.1 to 1.4 in Example 1.
2.5 Unvulcanized rubber: CHEMIGUM.RTM. NX 775
This is a carboxyl-containing NBR rubber from Goodyear Tire & Rubber,
Akron, Oh., USA. The properties of the product can be obtained from the
product data sheet "CHEMIGUM NX 775", published November 1987. An NBR
rubber containing filler and plasticizer is prepared on a mill at
60.degree. C. by mixing the following ingredients:
______________________________________
Parts by weight
Material
______________________________________
100 CHEMIGUM .sup..RTM. NX 775
40 VULKASIL .sup..RTM. C, a highly reactive
silica from Bayer AG, D-5090
Leverkusen
0.5 EDMA (ethylene glycol dimeth-
acrylate) from Degussa, D-6450
Hanau
1.0 Stearic acid
3.0 PERKADOX .sup..RTM. 40 (peroxide) from
Akzo-Chemie, Netherlands
______________________________________
2.6 Composite panels with rubber
To demonstrate the bonding action, composite panels are prepared by
covering the panels produced in 1.4 to the extent of one-third with a
Teflon film, placing a rubber hide of suitable dimensions on the panel,
preparing the composite by pressing and finally sawing off test pieces
having a width of 25 mm. These test pieces are subjected to a peel test in
accordance with DIN 53 539.
Result
The following properties are determined from Example 2:
__________________________________________________________________________
Unvulcanized
Vulcanizing temperature
Vulcanizing time
Bond strength in N/mm
Type of separation
rubber in .degree.C.
in min DIN 53 539 c = cohesive a = adhesive
__________________________________________________________________________
2.5 170 10 12.7 c
__________________________________________________________________________
The separation in the peel test (DIN 53 539) occurs cohesively, i.e. the
composite separates within the rubber component and not at the
plastic/rubber interface.
Furthermore, it is noted that although the rubber composition o molded
material B contains about 100 parts by weight of a rubber having carboxyl
or anhydride functional groups; about 10 to 300 parts by weight of
fillers; and about 1 to 10 parts by weight of peroxidic vulcanizing
agents, the rubber composition may also contain from 0 to 4 parts by
weight of vulcanization activators, from 0 to 150 parts by weight of
plasticizer; and optionally further additives which are known by customary
use.
Having described the present invention, it will be apparent to one of
ordinary skill in the art that many changes and modifications can be made
to the above described embodiments without departing from the spirit and
the scope of the present invention.
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